The present invention relates to a metal cylinder head gasket with a portion for holding an intermediate area between cylinder bores.
Metal laminate gaskets have been widely used in internal combustion engines due to strength against high temperature and pressure generated in the cylinder bores. Since high temperature and pressure are generated in the cylinder bores when the engine is actuated, the cylinder head gasket is provided with sealing means around the cylinder bore. There are many kinds of the sealing means, one of which has a flange around the cylinder bore. The flange may be integrally formed with one of plates for constituting the gasket, or a part of a grommet installed in the cylinder bore. The surface pressure around the cylinder bore is made high by the flange when the gasket is installed in the engine.
In the gasket with the flange, the flange may be located on an upper plate of the gasket to hold the upper plate. In this case, the upper plate is properly retained by the flange without any trouble.
However, there may be a gasket such that the flange is exposed outwardly of the gasket without being located above the upper plate. Namely, the upper plate is not held by the flange of the gasket around the cylinder bore. This structure is taken when the thickness of the gasket and the length between the cylinder bores are limited.
Especially, in a gasket formed of three metal plates or more, an upper plate which is not held by a flange extending from a lower plate or grommet may be slightly raised upwardly away from a middle plate between the cylinder bores. Under the high pressure and high temperature condition, if the middle portion between the cylinder bores is vibrated or subjected to high load repeatedly, the middle portion is weakened, so that the middle portion may be damaged or broken by fatigue destruction or fretting.
In view of the above, U.S. Pat. No. 5,295,699 was made. As shown in FIG. 6, the gasket is formed of two metal plates 110, 111.
The metal plate 110 has flanges 112 around cylinder bores Hc, and a pair of holes 116 at both sides of a middle portion 117 between the flanges 112. In the metal plate 111, one hole with projections 118 is formed without forming individual holes for the cylinder bores Hc. The projections 118 are inserted into the holes 116 to fix the projections 118 to the plate 110, so that the projections 118 do not deform nor vibrate.
However, in the above gasket, when the gasket is assembled, 20 the projections 118 must be inserted into the holes 116. Since the projections 118 face each other, the procedure for inserting the projections 118 into the holes 116 is relatively complicated.
The present invention has been made in view of the above, and an object of the invention is to provide a metal cylinder head 25 gasket, wherein an upper plate between the cylinder bores can be securely held without raising upwardly.
Another object of the invention is to provide a metal cylinder head gasket as stated above, wherein the upper plate between the cylinder bores is not damaged by vibration or load repeatedly applied thereto.
A further object of the invention is to provide a metal cylinder head gasket as stated above, wherein the gasket can be easily formed and assembled together.
Further objects and advantages of the invention will be apparent from the following description of the invention.